Petiole Junction | Backyard and Beyond

Petiole Junction

Published August 16, 2022 Uncategorized 2 Comments

Petiole, from the Latin for little foot, is, in zoology, a slender connection between two structures.

Yellow-legged Mud-dauber has one of the longer ones, at least around here. Check out, also, another of our local champions, Ammophila nigricans.

For the Apocrita, the narrow-waisted wasps, ants, and bees, the petiole is the “wasp-waist,” the tubular connection between the back end of the thorax (propodeum) and the abdomen. It can be of varying lengths.

The Great Black Digger, for instance, is one of our largest wasp species; the female is huge. But their petioles are relatively short.

Other species have ones so short they are not generally visible.

The botanically-minded may have gotten to here thinking, now, wait a minute! Because a petiole is also the stem of a leaf. Here is a particularly long example from a Norway Maple.

2 Responses to “Petiole Junction”

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1 Chuck McAlexander August 16, 2022 at 7:31 am

The only advantage to a long pettiole that occurs to me is increased range of motion between the thorax and abdomen. It might be helpful for mating or laying eggs but comes at a price, structural weakness. Like everything that evolves, the ancestors of these creatures have passed on a balance of the two elements which suited their lives. Now it is up to the current generation to do what they can with what they have inherited.

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2 Paul Lamb August 17, 2022 at 7:01 am

Chuck McAlexander answered the question I was going to ask.

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